1. Field of the Invention
The present invention relates to front end components in a semiconductor wafer fab, and in particular to a system allowing quick and easy installation, maintenance and removal of components within a minienvironment at a front end of a semiconductor processing tool.
2. Description of the Related Art
A typical semiconductor wafer fab includes a plurality of tool bays, each on the order of about eighty feet long, consisting in general of a number of processing tools for performing various wafer fabrication processes. The wafers are transported around the fab between the various processing tools within cassettes, which cassettes are themselves transported either bare or housed within enclosed containers. One type of conventional enclosed container is a so-called wafer lot carrier box which encloses the wafers but does not seal the wafers off against the fab environment. A second type of conventional container is a so-called standard mechanical interface (xe2x80x9cSMIFxe2x80x9d) pod which is sealed against the fab environment. A SMIF system offers several advantages including automated wafer transfer between pod and process tool while maintaining an ultraclean environment around the wafers.
Regardless of whether a fab is operating with open cassettes or containers such as lot boxes or SMIF pods, each processing tool in the fab includes front end equipment such as a minienvironment for facilitating transfer of the wafers or other workpieces between the cassette and the interior of the process tool. While front end minienvironments vary from fab to fab, such equipment may typically include a workpiece handling robot for transferring the workpieces between the cassette and the processing tool, as well as around the minienvironment; an aligner for identifying a center of the wafer and reading an optical code reader (xe2x80x9cOCRxe2x80x9d) or other fiducial mark on the workpiece; and power and control electronics for operating the minienvironment. The front end minienvironment may further include a fan/filter unit for controlling the environment within the equipment, and a vacuum reservoir for communicating a vacuum through the robot to secure a workpiece onto the robot end effector by suction. Various other application-specific components may further be provided within the minienvironment as required.
Each wafer fab typically includes hundreds of such minienvironments for the various processing tools, metrology tools, and stand alone stations within the wafer fab. As such, significant time and manpower is devoted to assembling and disassembling each of the minienvironments, as well as to maintaining each of the minienvironments in working order. This problem is made worse by the fact that, owing to the high cost of maintaining an ultraclean environment within the minienvironment, the space within the minienvironment is made as small as possible, and the components within the minienvironment are packed closely together. This makes installation, access and removal of a single component difficult, and often requires that one or more other components be removed before the subject component can be accessed.
In conventional systems, when it is necessary to exchange or repair for example a robot, at least two technicians are needed. First, they must gain access to the robot either by removing other components or maneuvering around the other components. Then they must delicately lift the robot, which can weigh over two hundred pounds, around other components and out of the minienvironment. This procedure is time consuming, difficult and can result in damage to one or more of the components.
It is therefore an advantage of the present invention to reduce the effort required to install, repair or remove a component from equipment such as a minienvironment on the front end of a processing tool.
It is another advantage of the present invention to reduce the time required to install, repair or remove a component from equipment such as a minienvironment on the front end of a processing tool.
It is a further advantage of the present invention to reduce the risk of damage to a component within equipment such as a minienvironment on the front end of a processing tool during installation, repair or removal of that or other components.
These and other advantages are provided by the present invention which in one embodiment relates to a system allowing quick and easy installation, maintenance and removal of components within a piece of equipment which may be attached to a front end of processing tool or may be a stand alone unit. In a first embodiment, the system includes a translation assembly and a pair of tracks fixedly mounted in frame of the equipment. The translation assembly in this embodiment includes a trolley having four wheels which ride on a portion of each of the tracks. When a component is to be assembled into the piece of equipment, the component is first bolted to the trolley. The trolley and attached component may then be inserted into the frame. The wheels riding on the tracks allow the robot to be quickly and easily moved to its proper position within the equipment. Once properly located, jackscrews threaded through the trolley are rotated to raise the trolley wheels off of the tracks, and to level the trolley and component. The trolley is then bolted down to the track and frame to securely fix the position of the component in the equipment.
In an alternative embodiment, the trolley and wheels are omitted, and instead a mounting plate supporting the component is provided which includes four ball casters at or near corners of the plate. The casters ride on the spaced apart tracks to allow easy loading and unloading of the robot into and from the frame. The casters are attached to the mounting plate via jackscrews which fit within threaded holes through the mounting plate. Once the robot is properly positioned within the frame, the jackscrews are rotated to lower the mounting plate until the plate is supported on vertical wall portions of the tracks and the casters no longer contact the tracks. The mounting plate may thereafter be bolted to the tracks to secure the mounting plate and component in a fixed position with respect to the tracks and frame.
A wide variety of components may be thus mounted into a piece of equipment for quick and easy installation, maintenance and removal, including for example, a workpiece handling robot, a workpiece aligner, a system controller, power and control components, pumps, vacuum reservoirs and environmental control units.